DYNAMICS OF DIFFUSION AND ADSORPTION: ZnO/α-Al2O3(0001)

摘要

A heteroepitaxial growth model of the ZnO film on sapphire(0001) is calculated by using a plane wave ultrasoft pseudo-potential method based on the density functional theory. A strong chemical adsorption on the sapphire(0001) is observed. It is found that interfacial atoms have different diffusivity at 400℃, 600℃ and 800℃. The temperature has a decisive effect on the surface and interface structures of ZnO/α-Al2O3(0001) and on the growth mode of ZnO thin films. In the whole process of the adsorption and growth of ZnO, the diffusivity of O atoms is higher than that of Zn, and the interlayer diffusion has an important impact on growth of the thin films. There are two growth modes of ZnO on sapphire(0001), which is further demonstrated by theoretical calculation. It can be observed from the calculation that the vacancies of Zn where the atomic layer is near to the α-Al2O3(0001) surface is more than that of O atoms.